Safe jump start

Page 243 of the owner's manual shows the jump starting procedure. As long as you have jumper cables, a booster battery, and your owner's manual when you jump start your Prius, you should have no reason to fear messing something up. Keep in mind that your battery might not accept a jump start if it has discharged too much or has failed internally.

 

Your Prius has no protection from you reversing the cables and doing $1000s of damage, so using 'smart' cables or a Jump pack is the safest way.

Amazon.com: Michelin 5100 Smart Jumper Cables with Surge Protection: Automotive

Schumacher XP400 400 Peak Amp Instant Portable Power Source : Amazon.com : Automotive

 

Smart cables are the only safe way to jump the Prius as stayed above by JimboPalmer. Failing that if using ordinary jump leads or even a jump pack make 100% certain you have got the other connections correct before the final connection. There is no second chance.
I know this sounds dramatic, but the cost of getting it wrong can be very high apart from the inconvenience.

John (Britprius)

 

One thing, I don't think jump packs as a group, have reversed polarity protection. I'd just be super careful to get it right: positive cable to positive (aka: red, plus symbol +), negative to ground (bare metal on engine, bare bolt or bracket on body).

 

Anyone use these?

Astro SP0612 Smart Plug 6 Gauge 12-Feet Booster Cables - Amazon.com they don't seem as foolproof as the Michelins, but as long as the center plug isn't connected together before the clamp connections are made to the vehicles then they seem to be "almost" foolproof.

SCH-I535

 

It is possible to get it wrong, but if you use the jump terminal under the hood, there is only one attachment point (it is for the positive cable). The negative has to go to a convenient point on the chassis. Getting it wrong is pretty hard to do.

 

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These are all in the last two weeks, I think you under estimate how badly people behave.

 

I'm not sure what prompted you to ask, but as you see with all the warnings above, if your 12-volt battery is starting to fail it is just prudent for a Prius owner to replace it instead of jump starting.
You can get lots of advice here on which battery to buy and how to install it your self if you're a do-it-yourselfer and save a lot of money over what the dealer charges. Prius 12-volt replacement is only marginally more difficult than most car batteries, especially if it is a direct OEM replacement. There are fans for both OEM and other brands here. Decide for yourself.